Putin strong at 60 but economic challenges loom

As he hits his 60th birthday, Vladimir Putin seems to be in the prime of life: He hang-glides with Siberian cranes, shows off judo moves and exudes supreme self-confidence at Russia's helm. But scratch the surface and a picture emerges of a surprisingly vulnerable leader whose fate hinges on the vagaries of oil prices and popular docility in the face of strong-arm tactics.